(1) Field of the Invention
The present invention relates to a wheelchair.
(2) Description of the Related Art
A conventional wheelchair comprises a chair body with a seat and armrests, right and left large wheels provided on right and left sides of said chair body, right and left front casters provided in front of said chair body, each of said front casters being adapted to turn in different horizontal directions.
However, the conventional wheelchair has the following disadvantages:
(A) When a user of the wheelchair is to move from the wheelchair to a bed, a chair, a toilet seat, a car seat, etc. (These will hereinafter be referred to as xe2x80x9cbed, etc.xe2x80x9d), he has to lift himself from the wheelchair and get up on his feet. Also, when he is to move from the bed, etc. to the wheelchair, he has to lift himself from the bed, etc. and get up on his feet. Such movements will impose a heavy burden not only on the user of the wheelchair but also on a person who helps him because it is impossible or difficult for the user of the wheelchair to walk. The burden will be very severe particularly when the user of the wheelchair is heavy and the helper is weak.
(B) Even when there is a small difference in floor height, a small projection, a small hole or any other small obstacle on the floor, the wheelchair may not be able to move across the obstacle because the front casters cannot get over the obstacle. Therefore, the wheelchair does not have freedom of movement.
(C) Since the large wheels of the wheelchair protrude sideways from the chair body, the large wheels may prevent the wheelchair from passing through a narrow space within a building, etc.
(D) Since the wheelchair is collapsible by folding the right and left sides of the chair body toward the inside, the seat and back of the chair body are made of a cloth or comprise a right and left pair of plates connected with one another so as to be collapsible. Therefore, the wheelchair is not comfortable to sit in.
(E) Since the large wheels of the wheelchair are not adapted to turn in different horizontal directions, the wheelchair cannot move sideways or obliquely.
It is therefore an object of the invention to provide a wheelchair, which has obviated all of the above-mentioned disadvantages of the conventional wheelchair.
It is another object of the invention to provide a wheelchair, which makes it possible for the user to move from the wheelchair to the bed, etc. or from the bed, etc. to the wheelchair without lifting himself and getting up on his feet.
It is a further object of the invention to provide a wheelchair, which can move across a small difference in floor height, a small projection, a small hole or any other small obstacle on the floor.
It is a still further object of the invention to provide a wheelchair, which can pass through a narrow space within a building, etc.
It is a still further object of the invention to provide a wheelchair, which is comfortable to sit in.
It is a still further object of the invention to provide a wheelchair, which can move sideways and obliquely.
These and other objects have been attained by the following wheelchairs.
First, the present invention is a wheelchair comprising a chair body with a seat and armrests, right and left large wheels provided on right and left sides of said chair body, right and left front casters provided in front of said chair body, each of said front casters being adapted to turn in different horizontal directions
wherein said chair body is provided at the rear thereof with right and left rear casters, each of said rear casters being adapted to turn in different horizontal directions, the position of each of said rear casters being vertically.
In this wheelchair, each of the rear casters is usually adjusted so that a lower end thereof is higher than a lower end of each of the large wheels. In this case, the rear casters do not contact the floor or the ground. Only the large wheels and the front casters contact the floor or the ground. Therefore, the wheelchair is used in the same manner as the conventional wheelchair.
If each of the rear casters is adjusted so that the lower end thereof is lower than the lower end of each of the large wheels, then the large wheels do not contact the floor or the ground. In other words, the wheelchair is supported only by the front casters and the rear casters. See FIGS. 1 and 2. Since both the front casters and the rear casters are adapted to turn in different horizontal directions, the wheelchair can move sideways and obliquely.
Second, the present invention is a wheelchair in which the position of each of said large wheels is adjustable forward and backward.
It is possible to adjust each of the large wheels to a position corresponding to the center of gravity of the wheelchair between the front casters and the rear casters. It is also possible to move each of the large wheels to a position in the rear of each rear caster. In either case, when the position of each of the large wheels is adjusted forward or backward, it is necessary to make the lower end of each rear caster lower than the lower end of each large wheel so that the large wheels do not contact the floor or the ground.
If each of the large wheels is adjusted to a position corresponding to the center of gravity of the wheelchair between the front casters and the rear casters and each of the rear casters is adjusted so that the lower end of each rear caster is higher than the lower end of each large wheel, then the wheelchair can be tilted forward and backward with the large wheels on the floor or the ground. When the wheelchair is tilted backward, the front casters are above the floor or the ground. When the wheelchair is tilted forward, the rear casters are above the floor or the ground. By tilting the wheelchair forward and backward in this way, the wheelchair can cross an obstacle on the floor or the ground. See FIG. 7.
Third, the present invention is a wheelchair in which each of said large wheels is attached to a horizontal supporting member, the position of said horizontal supporting member being adjustable forward and backward.
In order that the position of each of the large wheels is adjustable forward and backward, each of the large wheels is attached to a horizontal supporting member, the position of which member is adjustable forward and backward. Each of the large wheels moves forward and backward when each of the horizontal supporting members moves forward and backward.
Fourth, the present invention is a wheelchair in which each of said horizontal supporting members can be folded toward the inside of the wheelchair, and the diameter of each of said large wheels does not exceed the width of said chair body.
It is possible to fold each of the large wheels at the back of the chair body by moving each of the horizontal supporting members backward so that each of the large wheels is in the rear of the rear edge of the chair body and then bending each of the horizontal supporting members toward the inside of the wheelchair. When the large wheels are folded in this manner, the axles thereof are in a longitudinal direction. See FIGS. 4 and 5. Since one of the large wheels is folded and then another large wheel is folded at the back of said one of the large wheels, the horizontal supporting member for said another large wheel has a bending portion at a position in the rear of a bending portion of the horizontal supporting member for said one of the large wheels. See FIG. 3 and 4.
Since the diameter of each of the large wheels does not exceed the width of the chair body, each of the large wheels folded at the back of the chair body does not protrude sideways from the chair body. Usually each of the large wheels protrudes sideways from the chair body. Therefore, when each of the large wheels is folded at the back of the chair body, the overall width of the wheelchair becomes smaller. Thus, the problem that the large wheels prevent the wheelchair from passing through a narrow space within a building, etc. is solved. When the large wheels are folded at the back of the chair body, the user of the wheelchair cannot move the wheelchair by rotating the large wheels. In this case, the user of the wheelchair has to move the wheelchair by laying hands on a handrail, etc. or have a helper move the wheelchair.
Fifth, the present invention is a wheelchair in which said armrests are pivotally attached to right and left sides of said chair body so as to turn forward and backward.
When the large wheels are folded at the back of the chair body and the armrests are turned backward, the seat of the wheel chair is open sideways and has no obstacle sideways. See FIG. 5. Therefore, the user of the wheelchair can move from the wheelchair to the bed, etc. or from the bed, etc. to the wheelchair by sliding sideways. In other words, the user of the wheelchair does not have to lift himself and get up on his feet in order to move between the wheelchair and the bed, etc.
Sixth, the present invention is a wheelchair in which said chair body is collapsible backward.
When the large wheels are folded at the back of the chair body and the chair body is collapsed backward, the wheelchair becomes thin and compact. Since the seat and the back of the chair body are not folded, the seat and the back can be made of materials having a satisfactory cushioning effect.